1. Field of Invention
The present invention relates to a holographic photolithography apparatus to perform exposing using a hologram. More specifically, the invention relates to an apparatus to determine a quantity of filling liquid, such as index matching liquid or the like, to be used to bring a hologram mask into intimate contact with a prism, and filling the same.
2. Description of Related Art
A related art patterning process of a semiconductor device utilizes TIR (Total Internal Reflection) holographic exposure technology. This exposure technology includes a recording process in which a desired pattern is recorded on the hologram mask, and an exposing process in which regenerating light is irradiated on the hologram mask to expose a photoresist for a semiconductor pattern.
In the recording process, a recording beam, which is a laser beam, is irradiated onto a mask pattern (reticle) corresponding to a pattern of the semiconductor device to generate deflected light and emit the deflected light onto a recording surface of the hologram mask. On the other hand, a reference beam is irradiated from the rear of the hologram mask at a constant angle with respect to the recording surface of the hologram mask to interfere with the deflected light from the reticle. Accordingly, an interference pattern is generated on the recording surface of the hologram mask, which is recorded on the hologram recording surface.
In the exposing process, the hologram mask is placed at the same position as the reticle, and an exposure beam, which is the regenerating light, is irradiated from the opposite direction from the direction of irradiation for recording, and the deflected light, in which the original pattern is reproduced, is focused onto the photoresist.
Since the interference pattern, which is a specific reticle pattern, is recorded on the hologram mask, it is necessary to remove the hologram mask from the prism every time the pattern to be exposed is changed and bring a new hologram mask into intimate contact with the prism. In the related art, filling liquid whose optical characteristics can be adjusted to prevent it from affecting the refractive index, which is referred to as index matching liquid, can be used to bring the hologram mask into intimate contact with the prism.